I was out at the track today with a a friend, righteyeblind (reece) and I loaded the same tune that was in my truck in his, the only difference between the two trucks is that he has a single exit exhaust, I have duals and his is an 02 and mine is an 03. We make a pass and I put about 4 truck length on him about .5 seconds quicker. So I jump in his truck and log a pass. I noticed that his truck will not deliver the fuel requested, I have 3000ms commanded and its bouncing from 2000-2300ms. Also, it will not hold rail PSI even with lift pumps. My truck will hold 3000ms and 21,000psi so I am thinking their is a computer, tuning problem and I spent an hour trying to figure it out today with no luck. Just wondering if any of the experts have any ideas.

Thanks,
Bentley

Maybe his FPRV is weak and leaking but not dumping rail pressure? Just a guess since I'm not 100% sure how mechanically it works. Maybe he has a dirty fuel filter. Are you sure both of his lift pumps are lighting up?

I can hold 21kpsi with a 3200usec pulse and I have TTS lift pumps.

Maybe his FPRV is weak and leaking but not dumping rail pressure? Just a guess since I'm not 100% sure how mechanically it works. Maybe he has a dirty fuel filter. Are you sure both of his lift pumps are lighting up?

I can hold 21kpsi with a 3200usec pulse and I have TTS lift pumps.


You are comparing a LLY injection pulse to a LB7.....not a good comparison.

epb,
Did you use a script and make his tune with his OS? How do you know his lift pumps are working properly?

You are comparing a LLY injection pulse to a LB7.....not a good comparison.


Care to educate us on why? I know the injectors are different but not sure how.

I was wondering the same thing. Do the injectors make the big a difference.

I am not sure why we are talking LLY? What did i miss.

I am not sure why we are talking LLY? What did i miss.

Same here - we're talking an 02 and an 03.

Load the second tune as alternative comparison and see if anything is different.

I am not sure why we are talking LLY? What did i miss.

We're not. A statement was made and I want to know why it's true.

Does not sound like a computer program problem if one truck will maintain rail pressure and one won’t. The one that will not maintain PSI probably has a dirty fuel filter, weak lift pump, or weak CP3 pump (in that order). The LB7’s do not have an issue with the rail pressure relief valve like newer trucks do.

I was wondering the same thing. Do the injectors make the big a difference.
sure do!
Same here - we're talking an 02 and an 03.

Load the second tune as alternative comparison and see if anything is different.ya it would be worth haveing a look

Does not sound like a computer program problem if one truck will maintain rail pressure and one won’t. The one that will not maintain PSI probably has a dirty fuel filter, weak lift pump, or weak CP3 pump (in that order). The LB7’s do not have an issue with the rail pressure relief valve like newer trucks do.

i agree
i would start with the fuel filter for sure

Does not sound like a computer program problem if one truck will maintain rail pressure and one won’t. The one that will not maintain PSI probably has a dirty fuel filter, weak lift pump, or weak CP3 pump (in that order). The LB7’s do not have an issue with the rail pressure relief valve like newer trucks do.
Fuel filter was changed 8,000 miles ago. both pumps are coming on, working properly I don't know. I have only had them for 3 months. It can't be a weak cp3 because if the computer was commanding so much fuel and the cp3 can't keep up then the injectors would stay open longer to try to compensate not shorter.

epb,
Did you use a script and make his tune with his OS? How do you know his lift pumps are working properly?

Bob,

Yes it is written in his OS, its a DSP2 OS if that makes a difference.

Bentley

Fuel filter was changed 8,000 miles ago.

It only takes one bad tank of fuel to mess up a filter. ;)

Well guys, we found the problem. He has a weak CP3 and needs it replaced.

Bentley

Well guys, we found the problem. He has a weak CP3 and needs it replaced.

Bentley
Ouch!

Care to educate us on why? I know the injectors are different but not sure how. The LB7 injectors flow more than the LLY. Take an lb7 and an LLY main pulse map and compare. you will see the exact differences there.

The LB7 injectors flow more than the LLY. Take an lb7 and an LLY main pulse map and compare. you will see the exact differences there.
Thanks.

So I eat my words, cp3 was bad. just got it back from the dealer today. It held 160kpa on the freeway full throttle, with a little more conservative tune but it held. Tomorrow we're going to the track so we'll see hoe it does. I have had a weak cp3 for a while now because we have had problems trying to get it to hold rail pressure since I started using efilive. Thanks for you input.

Ya, i'd give my right eye if it wasn't the damned CP3!!! HAHA Reece! Thats crappy though, since you had to pay for it!

That is too bad. I wonder how many other people have had bad CP3's?

That's one of the beauties of EFILive. You can diagnose these types of things. Can't do that with a harness box or some of the hand held units.

That's one of the beauties of EFILive. You can diagnose these types of things. Can't do that with a harness box or some of the hand held units.

So whats the deal, you all love EFILive but all the LS2 guys bash it and love HPTuners...I love it for my SS! Apparently its too complicated for the HP guys to understand...kidding!